The present invention relates to diagnostic immunoassays of biological fluid samples which are utilized to detect more than one analyte at a time. Dual actions assays have been developed in the past, (U.S. Pat. No. 4,329,281, European Patent Application EPO, 165,716 A1, Syva Emit.RTM. Monoclonal Assay for Amphetamine/Methamphetamine and Roche Abuscreen.RTM. RIA for Amphetamine/Methamphetamine). These assays are configured by using two labels and two or more antibodies or antibody populations that are specific for each label.